pt2-web

A WebAssembly port of the ProTracker 2 clone — run the classic tracker in your browser.

This is a fork of 8bitbubsy/pt2-clone, modified to compile with Emscripten and run as a single-threaded web application.

What's different from upstream

The original pt2-clone is a native SDL2 desktop app. This fork adapts it for the browser:

• Main loop — driven by requestAnimationFrame from JavaScript instead of a native while loop. Exported entry points: pt2_loop_iteration(), pt2_load_file(), pt2_refresh_diskop().
• No worker threads — file listing, WAV rendering, and scope rendering run synchronously on the main thread. SDL_CreateThread() is not used.
• Modal dialogs — yield to the browser via emscripten_sleep() so the page stays responsive during blocking prompts.
• Audio — forward-progress guard prevents infinite audio callbacks if the tick counter stalls.
• Virtual filesystem — modules and samples are persisted via IDBFS (IndexedDB) to /persist/modules and /persist/samples. Survives page reloads.
• File loading — drag-and-drop or file picker in the browser. WAV renders are delivered as a direct browser download (Blob).
• Mouse input — canvas-relative coordinates (no desktop window position exists in the browser).
• VSync — delegated to the browser's requestAnimationFrame. SDL vsync is disabled to avoid errors.
• Cross-thread guards — spin-waits removed (deadlock-prone single-threaded) and drain guards added to prevent hangs on corrupt queues.

Building

Prerequisites

• Emscripten SDK
• SDL2 compiled for Emscripten

Build command

emcc src/*.c src/gfx/*.c src/smploaders/*.c src/modloaders/*.c \
  -O2 \
  -s USE_SDL=2 \
  -s ASYNCIFY \
  -s ALLOW_MEMORY_GROWTH=1 \
  -s EXPORTED_FUNCTIONS='["_pt2_loop_iteration","_pt2_load_file","_pt2_refresh_diskop","_main"]' \
  -s EXPORTED_RUNTIME_METHODS='["ccall","cwrap","FS","callMain"]' \
  -lidbfs.js \
  -I src \
  -o pt2.html

Notes:

• All four source directories must be included — omitting src/modloaders/*.c causes link errors.
• -lidbfs.js is required for the IDBFS (IndexedDB) persistence of /persist/modules and /persist/samples.
• EXPORTED_RUNTIME_METHODS exposes ccall/cwrap/FS/callMain so the host page can call the exported entry points and write picked files into the virtual filesystem.

(Adjust flags and source files to match your actual build setup.)

Running

Serve the output directory with any static web server and open it in a browser. Requires WebAssembly and IndexedDB support.

Credits

• Original pt2-clone — by 8bitbubsy (upstream repo)
• WebAssembly port — by ScottiDoes

License

See LICENSE — same as upstream.